The correct option is A Red
The Delhi Sultanate was predominantly spread in and around Delhi in North India and it gradually spread its rule across various parts of the Indian subcontinent for over three centuries. The architecture of Delhi Sultanate and Mughals shows extensive use of red sandstone. There are three monuments in Delhi which are regarded as world heritage sites — Qutub Minar, Red Fort and Humayun’s Tomb. All are made up of red sandstone.